Changeover switch

[Gareth J]

My understanding is that the iBoost outputs a DC voltage (not sure what 240?), surely that means the negative from the iBoost is not the same as the neutral from the mains?

The neutrals are shared, N in is connected directly to the immersion via a shared connector block. Whatever weird output the "positive" side of diverted PV is, the "negative" is the same neutral as mains neutral.

Suggestions that Joe might want to use a hive to boost the immersion may well be what's desired, but that doesn't make sense if he also wanted to control it manually via a changeover switch - I find his original description a bit confusing! I'm sure he'll be back to confirm the overall goal which will clear a lot up. Boosting via a hive or similar should be pretty straightforward.

[Gareth J]

This back from marlec

'am afraid your proposed installation will not work with the Solar iBoost.

I have attached a copy of the Installation Instructions for your perusal.

The ouput of the Solar iBoost+ is not standard 230VAC. It is a rectified AC which presents as DC and its PWM also.

It would not handle any sort of backfeed of 230VAC at all.

The Solar iBoost+ will need to be powered by continuous grid power, and must be connected directly to the immersion with no other devices between the unit and immersion.'

What they say is absolutely right - and it rules out designs (including one of mine) that use the hive to turn the iboost on/off. It'll be much more reliable if it's kept constantly alive to keep connection with the sender. I forgot about that!

However, they're wrong conclude you can't achieve what you want to, or that no "devices" can be connected downstream - they can be. For example a thermostat, or any switch can be connected downstream (within the limits of the switch) which will let you achieve what you want to.... what is it you're wanting to do exactly?!

[Joeboy]

Apologies, My description has been poor. At the moment My immersion coil in HWT is run off of a Hive plug to take advantage of the 5hr window on Go Faster. I had hoped to install an inline switch on that line to either send power from the hive switch to the immersion coil or to rotate a switch to Pos 2 and divert that power to the input side of my Solariboost unit to utilise excess PV on the same immersion coil. As the Iboost can't accept being backfed 240Vac it is more complicated. Essentially the idea was to have a simple Summer/Winter switch. The backfeeding is the showstopper...

It may be simpler to just rewire as I did for Winter this year. A switch would have been cooler.

The Hive switch was originally used to knock the Iboost off during night as it has the annoying habit of spooling up slightly and we can hear it in the bedroom. That same hive switch after a quick reroute of the power and adjustment of the Hive time now runs the 5 hour go faster window.

[Gareth J]

What about sunny winter days? Is there never a situation where you'd be feeding excess PV back to the grid because the the changeover switch is in the wrong position?

I think it'd be relatively simple to automate what you're after and not risk "throwing away" (well, generously giving back) PV to the grid during the winter position.

When is the go faster window?

And would you still like to stop hearing the iboost "sniffing" the export situation in the nighttime?

[Joeboy]

What about sunny winter days? Is there never a situation where you'd be feeding excess PV back to the grid because the the changeover switch is in the wrong position?

I think it'd be relatively simple to automate what you're after and not risk "throwing away" (well, generously giving back) PV to the grid during the winter position.

When is the go faster window?

That Winter scenario does not present itself, we are net consumers..Go faster is 21.30 to 02.30, I had intended to wait for changeover until we are seeing strong solar gains. I could do it with a make break switch between the Iboost and the immersion coil and another feed and same switch on the grid side. That creates the risk of me turning the wrong switch 1st and frying the iboost which I want to avoid! Im not in a hurry on this anyway. Got a dual battery chainsaw just arrived, gonna go cut a log or 2 to splitting size!

[Gareth J]

That should be relatively straightforward;




Use a relay (again, a 16 or ideally 20A one) that is activated when the hive turns on. It flips the Live side of the immersion to permenant live and boosts during the window you set on the Hive. Otherwise, it puts diverted PV into the tank. If you boost in the day, still no problem, as soon as the relay fires, the diversion live is disconnected.

The permenant live/neutral to the hive can come from the iboost or the source supply. I've drawn them from the source but there are spare terminals in the iboost it'll probably be easier to utilise.

If you wanted to eliminate nighttime hum, you could switch it about slightly and use the hive to isolate at night and the inbuilt iboost timer to organise the go-faster window. But then you'd loose the convenience of controlling the boost window via the hive .... Or buy a second hive to just cut the power in the nighttime - or is that a bit excessive!


Edit; actually if you want to eliminate nighttime hum AND use the hive to control the boosting, without buying another hive, you can switch it around and use the inbuilt iboost timer to isolate itself at night and then use the hive to feed 240v live into the immersion (presuming they're up to that?) Directly into the waiting relay. Will draw it for you later if interested

[Tinbum]

Isn't that what I suggested in post 21? I'd do the neutrals as well.

[Gareth J]

Isn't that what I suggested in post 21? I'd do the neutrals as well.

Just re-read - yes it is! Sorry, I didn't notice that. For the extra faff, and maybe cost of a DPDT relay, I wouldn't bother switching the neutrals. Have wired a few of these sorts of things here and always shared neutrals but it wouldn't hurt for sure.

[ALAN/ALAN D]

No need to switch Neutral.

[Countrypaul]

Given that the output from the iBoost is 240V DC will a normal 240V AC contactor be suitable, or would it require a "special" contactor suitable for 240V DC if it is to switch the iBoost output?